Fix natives for debug/pe

grantnelson-wf · grantnelson-wf · commit f5c911a46f9d · 2024-01-30T17:12:03.000-07:00
diff --git a/compiler/natives/src/debug/pe/symbol.go b/compiler/natives/src/debug/pe/symbol.go
@@ -0,0 +1,119 @@
+//go:build js
+// +build js
+
+package pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+// bytesBufferLite is a simplified bytes.Buffer to avoid
+// including `bytes` as a new import into the pe package.
+type bytesBufferLite struct {
+	data []byte
+	off  int
+}
+
+func (buf *bytesBufferLite) Write(p []byte) (int, error) {
+	buf.data = append(buf.data, p...)
+	return len(p), nil
+}
+
+func (buf *bytesBufferLite) Read(p []byte) (int, error) {
+	n := copy(p, buf.data[buf.off:])
+	buf.off += n
+	return n, nil
+}
+
+func copyToAuxFormat5(sym *COFFSymbol) (*COFFSymbolAuxFormat5, error) {
+	buf := &bytesBufferLite{data: make([]byte, 0, 20)}
+	if err := binary.Write(buf, binary.LittleEndian, sym); err != nil {
+		return nil, err
+	}
+	aux := &COFFSymbolAuxFormat5{}
+	if err := binary.Read(buf, binary.LittleEndian, aux); err != nil {
+		return nil, err
+	}
+	return aux, nil
+}
+
+func copyFromAuxFormat5(aux *COFFSymbolAuxFormat5) (*COFFSymbol, error) {
+	buf := &bytesBufferLite{data: make([]byte, 0, 20)}
+	if err := binary.Write(buf, binary.LittleEndian, aux); err != nil {
+		return nil, err
+	}
+	sym := &COFFSymbol{}
+	if err := binary.Read(buf, binary.LittleEndian, sym); err != nil {
+		return nil, err
+	}
+	return sym, nil
+}
+
+func readCOFFSymbols(fh *FileHeader, r io.ReadSeeker) ([]COFFSymbol, error) {
+	if fh.PointerToSymbolTable == 0 {
+		return nil, nil
+	}
+	if fh.NumberOfSymbols <= 0 {
+		return nil, nil
+	}
+	_, err := r.Seek(int64(fh.PointerToSymbolTable), seekStart)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to symbol table: %v", err)
+	}
+	syms := make([]COFFSymbol, fh.NumberOfSymbols)
+	naux := 0
+	for k := range syms {
+		if naux == 0 {
+			err = binary.Read(r, binary.LittleEndian, &syms[k])
+			if err != nil {
+				return nil, fmt.Errorf("fail to read symbol table: %v", err)
+			}
+			naux = int(syms[k].NumberOfAuxSymbols)
+		} else {
+			naux--
+			// The following was reading into one struct with the same memory
+			// footprint as another struck. This doesn't work in JS so the
+			// `syms` value is left with a bunch of defaults. So replace
+			// aux := (*COFFSymbolAuxFormat5)(unsafe.Pointer(&syms[k]))
+			// (an in memory remap) with the following read and then copy.
+			aux := &COFFSymbolAuxFormat5{}
+			err = binary.Read(r, binary.LittleEndian, aux)
+			if err != nil {
+				return nil, fmt.Errorf("fail to read symbol table: %v", err)
+			}
+			pesymn, err := copyFromAuxFormat5(aux)
+			if err != nil {
+				return nil, err
+			}
+			syms[k] = *pesymn
+		}
+	}
+	if naux != 0 {
+		return nil, fmt.Errorf("fail to read symbol table: %d aux symbols unread", naux)
+	}
+	return syms, nil
+}
+
+func (f *File) COFFSymbolReadSectionDefAux(idx int) (*COFFSymbolAuxFormat5, error) {
+	var rv *COFFSymbolAuxFormat5
+	if idx < 0 || idx >= len(f.COFFSymbols) {
+		return rv, fmt.Errorf("invalid symbol index")
+	}
+	pesym := &f.COFFSymbols[idx]
+	const IMAGE_SYM_CLASS_STATIC = 3
+	if pesym.StorageClass != uint8(IMAGE_SYM_CLASS_STATIC) {
+		return rv, fmt.Errorf("incorrect symbol storage class")
+	}
+	if pesym.NumberOfAuxSymbols == 0 || idx+1 >= len(f.COFFSymbols) {
+		return rv, fmt.Errorf("aux symbol unavailable")
+	}
+	pesymn := &f.COFFSymbols[idx+1]
+	// The following was reading one struct as another struct with
+	// the same memory footprint. This doesn't work in JS so the
+	// `rv` value is left with a bunch of `undefined`s. So replace
+	// rv = (*COFFSymbolAuxFormat5)(unsafe.Pointer(pesymn))
+	// (an in memory remap) with the following copy.
+	return copyToAuxFormat5(pesymn)
+}
